ECU MERCEDES-BENZ B-CLASS HATCHBACK 2021 Repair Manual

R
Perm issible gross weight of the trailer
R Maximum permissible speed of the trailer
Ensure thefo llowing before starting a journe y:
R The tyre pressure on there ar axle of theto w-
ing vehicle is set for a maximum load
R The lighting of the connected trailer is opera-
tional
R V
V ehicles wit
ehicles wit hout LED headlam
hout LED headlam ps or MUL
ps or MULTI-
TI-
BEAM LED headlam
BEAM LED headlam ps:
ps:the headlamps ha ve
been set cor rectly
In theev ent of increased rear axle load, the car/
trailer combination must not exceed a maximum
speed of 100 km/h forre asons conce rning the
operating permit. This also applies in countries in
which the permissible maximum speed for car/
trailer combinations is abo ve100 km/h. F F
olding t
olding t he ball nec
he ball nec k out and in
k out and in &
W
WARNING
ARNING Risk of accident due tothe ball
neck not being engaged
If th e ball neck is not engaged, the trailer may
come loose. #
Always engage the ball neck as descri-
bed. &
W
WARNING
ARNING Risk of injury from ball neck
swinging outwards
The ball neck may swing outwards when
unlocking or when it has not been proper ly
engaged.
There is a risk of injury within the ball neck's
ra nge of mo vement! #
Unlock the ball neck only when its range
of mo vement is unobstructed. #
Always be sure the ball neck is engaged
when folding in wards. *
N NOOTE
TE Increased risk of damage toprop-
erty due tofolded-out ball neck #
When the trailer is not coupled or the
bicycle rack is attached, fold in the ball
neck or, in the case of a fully electric
trailer hitch, retract the ball nec k. *
N
NO
OTE
TE Damage totheve hicle due toincor-
re ct use of the trailer hitch When a trailer hitch is used
toreco ver a vehi-
cle, theve hicle may be damaged in the proc-
ess. #
Use the trailer hitch only for pulling a
trailer or attaching appr oved car rier sys-
te ms (e.g. a bicycle rack ). R
R
eq
eq uir
uir ements:
ements:
R The vehicle is secured against rolling away.
R The swivel range is clear.
R The trailer cables or ada pter plugs ha vebeen
re mo ved. 274
274
Driving and parking

F
F
olding t
olding t he ball nec
he ball nec k out
k out #
Pull switch 2until the ball neck unloc ks.
The ball neck will fold out from under there ar
bumper.
Indicator lamp 1will 0ash. #
Pull the ball neck in the direction of the ar row
until it engages audibly in a vertical position.
Indicator lamp 1onthe ball neck release
switch will go out.
If th e ball neck is not securely loc ked in place,
th eTrailer coupling Check lockmessage will
appear on the inst rument displa y. #
Remo vethe co ver cap from the ball head and
store it in a safe place. Make sure
that the ball on the ball neck is clean.
Check that it is either greased or dry (g rease-
free), depending on the inst ructions forth e trailer.
F
F olding t olding t he ball nec
he ball nec k in
k in #
Pull switch 2until the ball neck unloc ks.
The ball neck will fold up under there ar
bumper.
Indicator lamp 1will 0ash. #
Push the ball neck in the direction of the
ar ro w until it engages audibly behind the
bumper.
Indicator lamp 1will go out and the message
on the inst rument display will disappear.
Obser vethe information about the displa yson the
inst rument cluster:
R Indicator and warning lamps (/ page 479)
R Display message s (/page 412) Coupling up/uncoupling a tr Coupling up/uncoupling a tr
ailer
ailer R
R
eq
eq uir
uir ements:
ements:
R The ball neck is extended and engaged in a
securely loc ked position. Driving and parking
275
275

Tr
ailers with a 7-pin plug can be connected tothe
ve hicle with thefo llowing adap ters:
R Adapter plug
R Adapter cable
The trailer will be cor rectly de tected bytheve hi-
cle only if thefo llowing conditions are met:
R The trailer is connected cor rectl y.
R The trailer lighting system is in working order.
The functions of thefo llowing systems will be
a.ec tedbya cor rectly connected trailer:
R ESP ®
trailer stabilisation
R Active Lane Keeping Assist
R Parking Assist PARKTRONIC
R Active Parking Assist
R Blind Spot Assist or Active Blind Spot Assist
R Drive Away Assist
R Cross Tra1c Ale rt
R Reversing camera
R 360° camera Coupling up a tr
Coupling up a tr ailer
ailer
* NO
NOTE
TEDamage tothe star ter battery due
to full dis charge Charging
the trailer battery using the po wer
supply of the trailer can damage the star ter
batter y. #
Do not use theve hicle's po wer supply to
ch arge the trailer batter y. #
Remo vethe co ver cap from the ball head and
store it in a safe place. #
Position the trailer on a le vel sur face behind
th eve hicle and couple it up totheve hicle. #
Open the soc ket cap. #
Inse rtthe plug with lug 1ingroo ve 3 on
th e soc ket. #
Turn bayonet coupling 2totheright as far as
it will go. #
Let the cap engage. #
Secure the cable tothe trailer with cable ties
(only if you are using an adap ter cable). #
Make sure that the cable is alw ays slack for
ease of mo vement during cornering.
Under thefo llowing conditions, a message may
appear on the inst rument display even if the
trailer has been connec ted cor rectl y:
R LEDs ha vebeen ins talled in the trailer lighting
system.
R The cur rent has fallen below the trailer lighting
system's minimum cur rent (50 mA).
% Accessories can be connected tothe perma-
nent po wer supply up to180 W and tothe
po we r supply that is switched on via the igni-
tion loc k. 276
276
Driving and parking

U
U
ncoupling a tr
ncoupling a tr ailer
ailer &
W
W ARNI NG
ARNI NGRisk of being crushed and
becoming trapped when uncoupling a
trailer
When uncoupling a trailer with an engaged
inertia-activated brake, your hand may
become trapped between theve hicle and the
trailer dr awbar. #
Do not uncouple trailers with an engaged
ove rrun brake. *
N
NO OTE TE Damage when uncoupling in a state
of ove rrun Uncoupling in a state of
overrun can damage
th eve hicle. #
Do not uncouple trailers with an engaged
ove rrun brake. #
Secure the trailer against rolling away. #
Disconnect the electrical connection between
th eve hicle and the trailer. #
Uncouple the trailer. #
Place the co ver cap on the ball head.
% T
Tr
railer
ailer s wit
s wit h LED lighting:
h LED lighting: aTer uncoupling the
traile r,switch theve hicle on and then o.
again. Bicy
Bicy
cle r
cle r ac
ack function
k function &
W
WARNING
ARNING Risk of an accident if the bicy-
cle rack is used incor rectly
The bicycle rack may become de tach ed from
th eve hicle in thefo llowing cases:
R the permissible load capacity of the trailer
hitch is exceeded.
R the bicycle rack is used incor rectl y.
R the bicycle rack is secured tothe ball neck
beneath the ball head.
Obser vethefo llowing foryo ur ow n sa fety and
th at of other road users:
R always adhere tothe permissible load
capacity of the trailer hitch. R
always obser vethe permissible rear axle
load of theto wing vehicle.
R use the bicycle rack only totransport bicy-
cles.
R always proper lysecure the bicycle rack by
attaching it tothe ball head.
R use only bicycle rack s appr ovedby
Mercedes-Benz.
R always obser vethe bicycle rack operating
instructions. *
N NOOTE TE Damage to, or crac kson, the trailer
hitch due tounsuitable bicycle rack s or
bicycle rack s being used inco rrectly #
use only bicycle rack s appr ovedby
Mercedes-Benz. *
N
NOOTE
TE Increased risk of damage toprop-
erty due tofolded-out ball neck #
When the trailer is not coupled or the
bicycle rack is attached, fold in the ball Driving and parking
277
277

neck or, in
the case of a fully electric
trailer hitch, retract the ball nec k. Depending on
the bicycle rack 's design, up to
th re e bicycles can be transpor ted on the bicycle
ra ck.
When mounted byattaching toball head 1,the
maximum load capacity is 75 kg. The maximum load capacity is calculated from
the
we ight of the bicycle rack and the bicycle rack
load.
Obser vethe no tes on driving with a roof load,
trailer or fully laden vehicle (/ page 173).
When using a bicycle rack , set the tyre pressure
fo r increased load on there ar axle of theve hicle.
Fu rther information on the tyre pressure can be
fo und in the tyre pressure table (/ page 376).
N
No ot tes on loading
es on loading
The lar gerth e distance between the load's centre
of grav ity and the ball head, thegr eater the load
on the trailer hitch.
Therefore, obser vethefo llowing no tes:
R mount heavy bicycles as close totheve hicle
as possible
R always distribute the load on the bicycle rack
as evenly as possible across theve hicle's lon-
gitudinal axis
Mercedes-Benz recommends removing all de tach-
able parts from bicycles (e.g. bask ets, ch ild seats,
re ch arge able batteries) before loading them onto
th e bicycle rack . This will impr ovethe aerody- namic
resis tance and centre of grav ity of the bicy-
cle rack.
Alw ays secure the bicycles toprev ent them from
moving around and check them at regular inter-
va ls to ensure that they are secure.
Do not use tarp aulins or other co vers. The driving
ch aracteristics and rear view may be impaired. In
addition, aerodynamic resis tance and the load on
th e trailer hitch will increase. Load distribution on
the bicycle rack
1 Vertical distance between centre of grav ity
and ball head 278
278
Driving and parking

F
F
unction of t
unction of t he pow
he power met
er meter (plug-in h
er (plug-in h ybr
ybrid)
id) 1
Combustion engine and electric mo tor
switched o.
2 Position in the display range of there co vered
energy
3 End of the display range of there co vered
energy
4 End of the display range of the combined out-
put of thehy brid system The
following functions of the po wer me ter are
per form ed:
R The po wer me ter supports you in electric-only
mode and displa ys the output obtained from
th ehy brid system.
R Regenerated energy is sh own in area 1–
3.
R When the po wer me ter needle is at position
1, theve hicle is switched o.. The combus-
tion engine and the electric mo tor are
switched o..
R Pow errange 3–4 show sth e combined
output of thehy brid system. F
F
unction of t
unction of t he electr
he electric mot
ic motor pow
or pow erav
er availability
ailability
displa
displa y (plug-in h
y (plug-in h ybr
ybrid)
id) 1
Start of the POWER display range
2 End of the POWER display range
3 Maximum recuperated energy
4 Start of the display range of there cuperated
energy
5 Current state of charge ofthe high-voltage
battery
R Area 1-2 shows th e output in electric
mode or boost mode. The POWER display sup-
ports you in electric-only mode.
R Area 3-4 shows th ere cuperated energy. 284 284
Instrument display and on-board computer

R
From point 3,the maximum recuperated
energy has been reached.
R The cur rent state of charge of high-voltage
battery 5is displa yed. Displa
Displa
ying t
ying the pow
he pow er met
er meter (plug-in h
er (plug-in h ybr
ybrid)
id)
On-board computer: 4 Content #
Select Power meter. Ov
Ov
er
ervie
vie w of display
w of display s in t
s in the ins
he ins tr
trument display
ument display
Displa yson the inst rument displa y:
u Active Parking Assist (/ page 269)
é Parking Assist PARKTRONIC deactivated
(/ page 267)
h Cruise control (/ page 232)
00CB Limiter (/ page 232)
ç Active Distance Assist DISTRONIC
(/ page 235)
00D4 Active Brake Assist (/ page 244) à
Active Steering Assist (/ page 241)
00B0 Active Lane Keeping Assist (/ page 255)
° Haptic accelerator pedal (/ page 179)
õ PLUG‑IN HYBRID operation activated
ò Sound generator inoperative (/ page 426)
00D6 ECO start/stop function (/ page 176)
00D9 HOLD function (/ page 228)
00CE Adaptive Highbeam Assist (/ page 143)
Ad aptive Highbeam Assist Plus
(/ page 144)
ð Maximum permissible speed exceeded (for
cer tain countries only)
V
V ehicles wit
ehicles wit h Speed Limit Assist:
h Speed Limit Assist: detected
instructions and tra1c signs (/ page 249).
V
V ehicles wit
ehicles wit h
hTr
Tra1c
a1c Sign Assist:
Sign Assist: detected instruc-
tions and tra1c signs (/ page 250). Head-up display
Head-up display
F
F
unction of t
unction of t he head-up display
he head-up display The head-up display projects
thefo llowing infor-
mation into the driver's /eld of vision abo vethe
cockpit, forex ample:
R The vehicle speed
R Information from the navigation system
R Information from the driving systems and driv-
ing saf ety sy stems
R Some warning messages
Depending on theve hicle's equipment, di.erent
content can be shown in theth re e areas of the
head-up displ ay (/page 286). Inst
rument display and on-board computer
285
285

Example: if
the option is switched on and a
ro ute toa new destination has been calcula-
te d, this destination would not be take n into
account forth e learning function.
Cr
Cr eating ne
eating ne w t
w themes
hemes #
Select ©. #
Select THEMES. #
Select 0081Set theme .
The settings which are sa ved in theth eme are
shown. #
Select Continue 0048. #
Select AudioandNavigation (Navigation) and
store the active settings in theth eme. #
Select Continue 0048. #
Select an entry screen. #
Select Continue 0048. #
Select an image. #
Enter the names into the entry /eld and con-
/rm with 0076. #
Select Save. Syst
Syst
em se
em se ttings
ttings Ov
Ov
er
ervie
vie w of t
w of t he sy
he syst
stem se
em se ttings menu
ttings menu In
the system settings menu, you can make set-
tings in thefo llowing menus and control ele-
ments:
R Display
- Styles
- Instrument lighting
- Display brightness
- Edge lighting
- Day/night design
R Control elements
- Keyboard language and handwriting recog-
nition
- Sensitivity of theto uchpad
- Sensitivity of theTo uch Controls
R LINGU ATRO NIC
R Sound
- Enter tainment
- Navigation and tra1c announcements -
Telephone
- Voice ampli/cation tothere ar
R Connectivity
- Wi-Fi, Blue tooth ®
, NFC
R Time & date
R Language
R Units for distance
R SoTware updates
R Data import/export
R PIN pr otection
R System Reset Inf
Inf
or
ormation on im
mation on im port
portant syst
ant syst em updat
em updat es
es Impor
tant system updates may be necessary for
th e security of your multimedia system's data.
Install these updates, or else the security of your
multimedia system cannot be ensured.
A system update consists of thre e steps:
R Downloading or copying of the data requ ired
fo r installation
R Installation of the downloaded system update MBUX multimedia system
297 297

%
The connection procedure may di.er depend-
ing on the device. Follow the inst ructions that
are shown in the displa y.Fu rther information
can be found in the manufacturer's operating
inst ructions. #
Select Internet settings . #
Select Connect via Wi-Fi . #
Select Add hotspot.
Connecting using a QR code
Connecting using a QR code #
Select the options 0048ofthe desired Wi-Fi
networ k. #
Select Connect using QR code. #
Scan the displa yed QR code with the device to
be connected.
The Wi-Fi connection is established.
Connecting using a secur Connecting using a secur itykey
ity key #
Select the options 0048ofthe desired Wi-Fi
networ k. #
Select Connect using security key. #
Have the security key displa yed on the device
to be connected (see the manufacturer's oper-
ating inst ructions). #
Enter this security key on the multimedia sys-
te m. #
Con/rm the entry with ¡.
Connecting using a WPS PIN
Connecting using a WPS PIN #
Select the options 0048ofthe desired Wi-Fi
networ k. #
Select Connect using WPS PIN input.
The multimedia system generates an eight-
digit PIN. #
Enter this PIN on the device tobe connected. #
Con/rm the entr y.
Connecting using a butt
Connecting using a butt on
on #
Select the options 0048ofthe desired Wi-Fi
networ k. #
Select Connect via WPS PBC. #
Select "Connect via WPS PBC" in the options
on the device tobe connected (see the manu-
fa cturer's operating instructions). #
Press the WPS button on the device tobe con-
nected. #
Select Continue inthe multimedia system.
A
A ctiv
ctiv ating aut
ating aut omatic connection
omatic connection #
Select Connect via Wi-Fi. #
Select the options 0048ofthe desired Wi-Fi
networ k. #
Activate Permanent Internet connection .
Connecting wit
Connecting wit h a kno
h a known W
wn Wi-F
i-Fi ne
i ne tw
twork
ork #
Select Connect via Wi-Fi. #
Select a Wi-Fi networ k.
The connection is established again.
Con/gur
Con/gur ing
ingt
the multimedia syst
he multimedia syst em as a W
em as a Wi-F
i-Fi ho
i ho t-
t-
spo
spo t f
t for e
or e xt
xter
er nal de
nal de vices
vices
The type of connection established depends on
th e device tobe connected. The function must be
suppor tedby the multimedia system and bythe
device tobe connected. The type of connection
established must be selected on the multimedia
system and on the device tobe connected. #
Select Vehicle hotspot. MBUX multimedia system
299 299

#
Select Connect device to vehicle hotspot.
Connecting using WPS PIN g
Connecting using WPS PIN g ener
eneration
ation #
Select Connect using WPS PIN generation. #
Enter the PIN shown in the media display on
th e device tobe connected and con/ rm.
Connecting using WPS PIN entry
Connecting using WPS PIN entry #
Select Connect using WPS PIN input. #
Enter the PIN that is shown on theex tern al
device's displ ayon the multimedia system.
Connecting using a butt
Connecting using a butt on
on #
Select Connect via WPS PBC. #
Press the push button on the device tobe
connected (see the manufacturer's operating
inst ructions). #
Select Continue .
Connecting using a secur
Connecting using a secur itykey
ity key #
Select Connect device to vehicle hotspot.
A secu rity key is displa yed. #
Select theve hicle from the device tobe con-
nected. The vehicle is displ ayed with the
DIRECT-MBUX XXXXX network name. #
Enter the security key which is shown in the
media display on the device tobe connected. #
Con/rm the entr y.
Connecting using NFC
Connecting using NFC #
Select Connect via NFC. #
Activate NFC on the mobile device (see the
manufacturer's operating instructions). #
Hold the device tobe connected at theve hi-
cle's NFC inter face. #
Select Finished.
The mobile device is now connected tothe
multimedia system hotspot via NFC.
Gener
Gener ating a ne
ating a ne w secur
w securitykey
ity key #
Select Vehicle hotspot. #
Select Generate security key.
A connection will be established wi th the
ne wly created security key. #
T To sav o sav e a secur
e a secur itykey
ity key :
:select Save.
When a new security key is sa ved, all existing
Wi -Fi connections are then disconnected. If
th eWi -Fi connections are being re-estab-
lished, the new security key must be en tere d. Syst
Syst
em language
em language N
No
ot
tes on t
es on t he syst
he syst em language
em language
This function allo wsyouto determ ine the lan-
guage forth e menu displa ysand the navigation
announcements. The selected language a.ects
th ech aracters available for entr y.The navigation
announcements are not available in all languages.
If a language is not available, the navigation
announcements will be in English.
Se Se tting t
tting t he syst
he syst em language
em language
Multimedia system:
4 © 5
Settings 5
System
5 00A7 Language #
Set the language. 300
300
MBUX multimedia system